Distance between two points

gistfile1.js

function getDistance(point1,point2){
	var my = ((point1.lat + point2.lat) / 2.0) * Math.PI / 180.0;
	var dy = (point1.lat - point2.lat) * Math.PI / 180.0;
	var dx = (point1.lng -  point2.lng) * Math.PI / 180.0;
	var w = Math.sqrt(1.0 - 0.0066943799901975 * Math.pow(Math.sin(my),2));
    	return Math.sqrt(Math.pow(dy * 6335439.32729246 / Math.pow(w,3),2) 
		+ Math.pow(dx * 6378137.000 * Math.cos(my) / w,2));
}